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This is the mechanical room of the Empire State building, which underwent a multi-million dollar renovation project in 2009. The mechanical system upgrade was done to reduce energy consumption by 38 percent and allow the Empire State Building to enter the top 10 percent of eco-friendly offices.

EMMANUEL DUNAND/AFP/Getty Images

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Despite the enormous changes in building heating- and cooling-load patterns in modern buildings, HVAC systems continue to be configured very much the same way as they were generations ago. Then, the building envelope, lighting, and plug loads dominated the thermal balance in commercial structures. In today’s more efficient commercial buildings, the thermal influence of envelope, lighting, and plug loading has fallen so dramatically that in many efficient buildings occupants now dominate the thermal load.

When control capabilities were limited and non-occupant loads dominated building heating and cooling, it made sense to set up building-wide occupancy schedules, and apply HVAC resources to condition and ventilate buildings more or less uniformly during scheduled occupancy. But with the changes in technology and thermal loads, and the requirement for more efficient buildings, our industry sorely needs new HVAC systems!

So let’s start by considering the paradigm shift possible in HVAC systems as the occupants themselves become the dominate element in the thermal equation of building spaces. The need for general space conditioning fades and it becomes possible to direct both thermal and ventilation resources entirely to the building occupants - whenever and wherever they are in the building. Modern controls make it easy to determine when and where occupants are in the building. The only sticking point is that most current HVAC system components available today are intended for general building conditioning. It is both difficult and expensive to reconfigure these components for more specific occupant-based conditioning. What’s really needed is an entirely new kind of HVAC system.

I was recently introduced to a new spin on old dual duct technology. In Europe, a company founded in the Netherlands by Albert Bauer was acquired by Robert Bosch, LLC about a year ago. They call it a dual channel system using a 1/3 & 2/3 capacity supply duct in conjunction with BAOPT (Bauer Optimization Technology) patented control algorithms. The two ducts can be either both hot, both cold, either one hot or cold, both active or only one active depending on the space loads. They utilize space temperature, RH, C02, occupancy, damper position and space pressure sensors to control the airflow and don't use any airflow measuring stations to track supply and return fans. To date, most of the installations have been retrofit projects in Germany, Australia, and China. They were looking for a site in North America to install it and it was recently bid as an alternate for an addition to a Bosch R&D facility expansion we designed in the US but the bids came in at almost $500,000 or the base controls system design for a 100,000 sq. ft. office building so it wasn't accepted.

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